Fix very long app_name crash.

http://ibrahimbalic.com/2014/android-os-memory-corruption-bug/ found an stack overflow bug.
The very long app_name make libandroid_runtime allocate a very large array on stack, the stack may overflow to other data areas in this situation.
This patch allocate large array on heap instead of on stack to avoid segment fault when doing memcpy.

Change-Id: I99999569b852d43a9c7a6eb1fa80e9f1a1f4e2b2